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94 Cards in this Set
- Front
- Back
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DNA Profiling |
technique employed by forensic scientists to assist in the identification of individuals by their respective DNA profiles |
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Introns |
non-coding blocks |
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Exons |
Coding regions for proteins |
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STRs |
Short tandem repeats (short DNA sequences repeated many times within introns |
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Restriction enzymes |
enzyme produced by bacteria to cut DNA at exact place |
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Polymerase chain reaction |
process in which DNA is copied numerous times using DNA primers |
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DNA primers |
short DNA sequences complementary to the DNA adjacent to the STR They are marked with fluorescent tags and identify the sequence you want to copy |
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DNA Polymerase |
enzyme from bacteria that can survive high temperatures and is therefore used in the PCR |
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Gel Electrophoresis |
process in which the DNA fragments produced by the PCR can be separated |
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Sigmoid curve |
curve in which a cooling body follows |
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Rigor Mortis |
after death the muscles totally relax then stiffen, the stiffening is called rigor mortis |
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Autolysis |
when the body's own enzymes from the digestive tract and lysosomes break down cells |
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Tuberculosis (TB) |
an infectious bacterial disease characterized by the growth of nodules (tubercles) in the tissues, especially the lungs |
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Human immunodeficiency virus (HIV) |
causes the acquired immunodeficiency syndrome (AIDS) a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. |
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AIDS |
active form of HIV in the body affecting the immune system |
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Host cell |
a cell in which a virus multiplys |
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antigens |
a toxin or foreign substance which induces an immune response in the body, especially the production of antibodies. |
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Lysis |
the disintegration of a cell by rupture of the cell wall or membrane. |
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Pathogens |
a bacterium, virus, or other microorganism that can cause disease |
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Lysozyme |
enzyme found in secretions which attacks bacteria by breaking down their cell walls |
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Inflammatory response |
helps to destroy invading microbes |
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Phagocytosis |
white blood cells that engulf bacteria and other foriegn matter in the blood and tissues |
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Neutrophils |
leave the capillaries by squeezing between cells in walls |
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Macrophages |
start as monocytes and then squeeze out of capillaries and become macrophages |
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Lymph nodes |
a number of small swellings in the lymphatic system where lymph is filtered and lymphocytes are formed |
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Interferon |
antimicrobial protein that provides non-specific defence against viruses |
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Lymphocytes |
white blood cells that help to defend the body against specific diseases |
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B Cells |
type of lymphocyte secrete antibodies in response to antigens produce only one type of antibody produced in bone marroT |
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T Cells |
type of lymphocyte produced in bone marrow then mature in thymus gland have one specific type of antigen receptor on surface |
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immunoglobins |
special protein molecules antibodies are immunoglobins bind to antigens on the cell surface membrane |
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T Helper cells |
stimulate B cells to divide and produce antibodies enhance activity of phagocytosis |
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T Killer cells |
destroy any cells with antigens on their surface membrane that are recognised as foriegn |
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antigen-presenting cells (APCs) |
macrophages displaying non-self peptides |
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T Memory cells |
remain in the body for months or years if exposed to same antigen in the future, the immune system can respond quicker |
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Cytokines |
chemicals released by T helper cells to stimulate division and differentiation of B cells |
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B Effector cells |
differentiate to produce plasma cells release antibodies into blood and lymph only last a few days |
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B Memory cells |
longer lived - remain in body for months or years enable individual to respond quicker in future |
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clonal selection |
the process of B cell division |
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primary immune response |
production of sufficient antibody-producing cells |
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secondary immune response |
B cells produced in primary immune response differentiate and release antibodies memory cells produced
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immune |
when virus of bacteria is destroyed so rapidly that the person is unaware of the symptoms |
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apoptosis |
programmed cell death |
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Hypothalamus |
section of the brain responsible for hormone production, temperature etc
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reverse transcriptase |
enzyme used in reversing the normal transcription to manufacture DNA from RNA |
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Intergrase |
enzyme used when integrating the new strand of DNA into the host's DNA |
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RNA Polymerase |
Enzyme that allows the separation of the DNA strands |
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opportunistic infections |
diseases that take advantage of the weakened immune system |
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Skin flora |
microbes that live on the skin surface prevent colonisation of bacteria |
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Gut flora |
bacteria found in the small and large intestines conditions ideal in the gut bacteria aids digestive process and compete with pathogens for food |
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active artificial immunity |
immunity via vaccines |
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passive artificial immunity |
vaccine given in the situation where you may have already caught the disease |
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active natural immunity |
immune response helps destroy the virus and immune to it in future e.g chickenpox |
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passive natural immunity |
antibodies crossing the placenta from mother during pregnancy |
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Herd immunity |
group protection against virus or disease |
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Bactericidal |
antibiotics destroy bacteria |
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Bacteriostatic |
antibiotics prevent the multiplication of bacteria the host's immune system can then destroy them |
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conjugation |
bacteria do not undergo sexual reproduction that animals do the have cell-to-cell contact called conjugation |
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How is the DNA sample obtained? |
- from biological tissue - broken down with buffer solution - suspended particles separated using centrifuge - protease enzymes remove proteins - cold ethanol precipitates out DNA - DNA washed in buffer solution |
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How are the Fragments created? |
- restriction enzymes - cut up DNA - if restriction sites are either side of short tandem repeat sequence - stay intact |
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What happens during the polymerase chain reaction? |
- DNA copied using DNA primers - sample placed in tube with DNA polymerase, primers and nucleotides - PCR machine - temperature changes - hot - separates strand then cold creates fragment then 75 |
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How do you separate the fragments? |
- gelelctrophoresis - DNA placed on gel - provides stable medium in which fragments can move - gel submerged in buffer - electrodes produce positive difference - DNA fragments move according to charge |
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How to visualise the fragments? |
- southern blotting - membrane placed onto gel - draws buffer solution up through gel - carries fragments onto membrane - membrane incubated with labelled DNA probe - short section of DNA with complementary bases - probe binds complementary bases then is washed away |
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What does the sigmoid curve assume? |
every body is 37 degrees at death |
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What factors affect the cooling of a dead body? |
- clothing - body position - humidity - body size - temp of surroundings |
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What is the process of rigor mortis? |
- after death muscles starved of oxygen - respiration in cells now anaerobic - lactic acid - pH of cells falls, inhibiting enzymes and therefore inhibiting anaerobic respiration - ATP needed for muscle contraction not produced - proteins can no longer move over one another - fixed joints |
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What is Putrefaction? |
greenish discoloration of skin of lower abdomen due to the formation of sulphaemoglobin in blood |
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What factors affect the number of insects on the body? |
- season - weather - size - conditions of body |
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What do prokaryotic cells NOT have? |
- nucleus - membrane bound organelles - do not produce spindle in division |
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How do prokaryotic cells reproduce? |
Binary fission - after replication of DNA they divide into identical cells |
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What do viruses contain? |
- nuclei acid - protein coat - some have outer membranes from host cell |
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How does a virus get into a cell? |
- attaches to host cell - inserts nucleic acid - nucleic acid replicates - protein coat synthesises - new virus particles formed - virus particles released due to lysis |
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What are examples of non-specific responses? |
- lysozyme - inflammation - phagocytosis |
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What is the primary immune response of T Cells? |
- macrophages engulf material - protein fragments attach to proteins form cells - on surface membrane (APCs) - T Helper cells with complementary receptor binds to antigen - T Helper divides to produce T Helper cells and T memory cells |
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What is the primary immune response of B Cells? |
- receptors on surface bind to antigens on T helper and become APCs - T Helper cells release cytokines which stimulate division into B effector and B memory cells - clonal selection |
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What do T Killer cells do? |
- bind to antigen on body cell - divide to form active clone - stimulated by cytokines - release enzymes that create pores in membrane - ions and water enters cell which leads to lysis - Pathogens within cells released - labelled by antibodies - destroyed by macrophages |
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What are memory proteins? |
- act a bar codes as they distinguish between own cells and foreign invaders |
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Why can TB bacteria survive for years inside the body? |
- taken up by phagocytosis - resist killing mechanisms - thick and waxy walls difficult to break down |
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What are the symptoms of TB? |
- coughing - shortness of breath - loss of appetite - fever and extreme fatigue |
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How are skin tests carried out? |
- small amount of tuberculin injected into skin - poisitive result shows inflamed area - shows TB antigens present |
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What is the structure of an HIV virus? |
- glycoproteins - lipid bilayer - viral proteins - layer of viral protein - two copies of mRNA - caspid made up of protein units |
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How does HIV invade T Helper cells? |
- glycoprotain molecules bind to CD4 receptors - combine with second receptor - envelope surrounding viral fuses with T helper cell membrane - Viral RNA enters cell - reverse transcription - integration - new DNA transcipted and translated to produce viral proteins |
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What happens during Transcription? |
- RNA ploymerase allows DNA to unwind - RNA nucleotides to pair up to form mRNA - mRNA leaves nucleus through pore in membrane - attaches to ribosome |
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What happens during translation? |
- tRNA complementary bases bind to mRNA - peptide bonds form between amino acids tRNA leaves |
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Non-overlapping |
No base in one triplet is also part of the next |
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degenerate |
several triplets can code for the same amino acid |
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How does a virus destroy T Helper cells? |
- viral proteins produced - assemble into new viruses - new viruses bud out of T Cell, taking some of membrane with it - kill cell as they leave - can also be destroyed by T Killer cells |
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What happens during the acute phase of HIV? |
- HIV antibodies appear in blood - symptoms become apparent - rapid replication of virus and loss of T Helpers cells - infected T Helper cells recognised by T Killer cells and destory them |
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What happens during the chronic phase of HIV? |
- may be no symptoms but increasing infections - dormant diseases reactive - can last for years |
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What happens during the disease phase of HIV? |
- increase of viruses and decrease of T helper cells indicated AIDS - immune system vulnerable - more susceptible to cancerous tumours |
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How does the skin prevent infection? |
- keratin hard outer layer - blood clotting - skin flora |
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How does mucous membranes prevent infection? |
- cillia and mucus move microoganisms down into stomach |
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How does gut flora prevent infections? |
-aid digestive processes - compete with pathogens for food |
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What is an attenuated virus vaccine? |
weakened so they are harmless |
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What drugs are available to treat AIDS? |
- reverse transcriptase inhibitors - prevent RNA to DNA - protease inhibitors - stops cutting of proteins |
